Conventionally, there are a variety of methods for determining water content of powder and particles ground from wood chip available as the material of paper including the absolute dry method, electric current measuring method, neutron-applying method, and the microwave-irradiating method mentioned above. When measuring the water content by irradiating microwave, since the objective sample is directly set inside of a waveguide, some particles of the sample adhere to the inner wall of the waveguide as residue to eventually cause error to occur in the course of rating the water content of sample of other material in the following test. Furthermore, when directly inserting sample into the waveguide, since the sample may be leant to any one or two sides of the waveguide, it is difficult for the operator to uniformly set the sample in the waveguide, and thus, the resulting error also occurs.
The object of the invention is to fully solve those problems mentioned above present in any of conventional water-content determining apparatuses by irradiating a microwave to a sample of powder/granule material using a novel apparatus which is capable of easily and precisely measuring water content of powder/granule sample.